Skip to content

Pi OS Essentials

Raspberry Pi OS is Debian with Pi-specific tuning. If you know Debian/Ubuntu, you know 95% of it. This chapter covers the Pi-specific 5% and the first-hour setup.

First boot checklist

sudo apt update && sudo apt full-upgrade -y

Then reboot if the kernel updated (uname -r before and after tells you). After that:

sudo raspi-config

The settings worth touching:

  • System → Hostname — if you didn't set it in Imager
  • Interface Options → SSH — confirm it's on (headless depends on it)
  • Performance → GPU Memory — on a headless server, drop this to 16MB. The default reserves 76MB+ for a desktop you'll never see; that's RAM back for your services
  • Localisation — timezone and Wi-Fi country (the wrong Wi-Fi country can disable 5GHz channels)

The 64-bit check (again, because it matters)

uname -m

aarch64

And confirm you're actually using the RAM you paid for:

free -h

               total        used        free      shared  buff/cache   available
Mem:           3.7Gi       ...

A "4GB" Pi shows ~3.7GiB (some goes to the GPU/CPU reservation). If you see ~1GB on a 4GB board, something's wrong — usually the GPU memory split set absurdly high.

Storage: treat the SD card as fragile

SD cards wear out and corrupt on power loss. Two habits:

  1. Back up the card before big changes: bash # from your regular computer, with the card inserted: sudo dd if=/dev/sdX of=pi-backup.img bs=4M status=progress (Replace /dev/sdX with the card's device — lsblk to find it. Getting this wrong overwrites the wrong disk.)
  2. For anything you care about, boot from better storage: Pi 5 → NVMe via the PCIe HAT; Pi 4 → USB 3.0 SSD. Both are an order of magnitude more reliable than SD.

Keep it updated, automatically

sudo apt install unattended-upgrades

It installs security updates on its own. Check occasionally that it's actually running (systemctl status unattended-upgrades) — "set and forget" only works if the "set" part happened.

What Raspberry Pi OS is not

It's not a rolling release and not minimal — it's stable Debian with a friendly face. For containers and servers that means: slightly older packages, rock-solid behavior. If you need the newest everything, that's what the Docker guide is for — run new software in containers on a boring, stable host.